Seaweed emits a natural chemical response to ward off fungi that would otherwise colonize an injured plant, a process that could help the search for antimalarial drugs, a US scientist has said.

Up to a million people per year die from malaria, which can be caused by the parasite Plasmodium falciparum, and new drugs are needed because the parasite is developing resistance to popular pharmaceuticals.

"There are only a couple of drugs left that are effective against malaria in all areas of the world, so we are hopeful that these molecules will continue to show promise as we develop them further as pharmaceutical leads," scientist Julia Kubanek, an associate professor at Georgia Tech, said on February 21.

Researchers discovered the class of seaweed defense compounds, known as bromophycolides, by studying 800 species of seaweed off Fiji Island.

One type in particular caught their attention, Callophycus serratus, "because it seemed particularly adept at fighting off microbial infections," said the study presented Monday at an international science conference in Washington.

The molecules appeared in light-colored blotches on certain parts of the seaweed, and were visible with the help of a new technique known as desorption electrospray ionization mass spectrometry developed at Georgia Tech's School of Chemistry and Biochemistry.

"The alga is marshalling its defenses and displaying them in a way that blocks the entry points for microbes that might invade and cause disease," said Kubanek.

"Seaweeds don't have immune responses like humans do. But instead, they have some chemical compounds in their tissues to protect them," she said.

"We can co-opt these chemical processes for human benefit in the form of new treatments for diseases that affect us."

However, more research needs to be done before the process can be turned into a drug for humans, and studies on mice are planned next.

"As with other potential drug compounds, however, the likelihood that this molecule will have just the right chemistry to be useful in humans is relatively small," said the study.

The research was funded by the National Institute of Health as part of a long-term study of chemical signaling among organisms in coral reefs.

In January, the World Health Organization launched a global plan to halt the spread of resistance to artemisinin, a key compound of new malaria drugs, warning that not acting would be "catastrophic."

Resistance has emerged in areas on the Cambodia-Thailand border, while a spread to other areas in Cambodia, Myanmar, Thailand and Vietnam is suspected.

The WHO said more than US$175 million in funding would be required for research and to contain the resistance in these areas.